The body was found in a retention pond at the southbound off-ramp of Interstate 75 and SR 70.
Manatee County Sheriff Rick Wells said the body appears to be that of a man, but the identity of the person has not been confirmed.
ABC11 spoke with an FBI expert about the likely process of the investigation. Retired special agent Frank Brostrom said, unlike other missing persons cases, knowing who he was with and when he left gives investigators a good starting point.
"Normally in these kinds of investigations, you have somebody disappears, you have no leads, you don't know who was with them last, you don't know where they were last, and you're kind of starting from scratch," Brostrom said.
Since the cousins Gio were with had already spoken with investigators, any evidence they later find gives them a chance to compare with what the cousins claim happened.
"They're going to do phone work on everybody involved, talk to any witnesses, and they've got some great leads," he said.
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ABC11 spoke with Gio's stepdad, Jeremy Brown, on Thursday, who said while they were a little skeptical of Gio going with cousins he hadn't met, he was excited to spend time with them when he left that night.
"We had our reservations, but we trust you, we trust you're going to look out for yourself, we trust you're going to be safe," Brown said.
Law enforcement experts say the part of the story from his cousins about Gio's alleged erratic behavior isn't adding up.
"Adding that he pulled a knife on us and then he's the one texting help, I need help, that story's not going to stand up," Brostrom said.
And he says one way or another, the truth will come out.
"Their stories are in cement and the investigators are going to work around those stories and compare it to the evidence, basic investigations one on one," Brostrom said.
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